The present invention relates to a backside covering member to be used as a protective member for protecting back sides of solar cells of a solar battery, a sealing film and a solar battery employing the backside covering member. More particularly, the present invention relates to a backside covering member and a backside covering and sealing film which is excellent in moistureproof property and durability, further has good insulation performance, and does not cause leakage of current, and a durable, high-performance solar battery using the aforementioned backside covering member as a protective member.
In recent years, solar cells which directly convert sunlight to electric energy are drawing the attention of people in view of effective utilization of natural materials and prevention against environmental pollution and thus its development is promoted.
A typical solar battery comprises a glass substrate 11 as a front side transparent protective member at a light-receiving side, a back side protective member (backside covering member) 12, ethylene-vinyl acetate copolymer (EVA) films 13A, 13B as sealing films arranged between the glass substrate 11 and the back side protective member 12, and solar cells or silicon photovoltaic elements 14 sealed by the EVA films 13A, 13B.
To manufacture this solar battery, the glass substrate 11, the sealing EVA film 13A, silicon photovoltaic elements 14, the sealing EVA film 13B and the backside covering member 12 are successively overlaid in this order and integrated together by heating and crosslinking the EVA.
The backside covering member 12 for solar battery is a resin film made of polyethylene monofluoride, white polyester, or the like for achieving light weight and thin wall.
It is primarily required for the backside covering member 12 to have excellent moistureproof property for preventing inside wirings or electrodes from corroding due to moisture and/or water permeation in addition to light weight and enough durability. However, the conventional resin film as the backside covering member can not have enough moistureproof property.
Generally known as moistureproof film is a film made by forming a metal coating film of material such as aluminum on a base film. However, when such a moistureproof film using metal such as aluminum is applied to a solar battery, there is possibility of current leakage. Accordingly, such a moistureproof film is inadequate as a moistureproof film used in a solar battery.
The object of the present invention is to provide a backside covering member and a backside covering and sealing member, to be used as a protective member for protecting back sides of solar cells of solar battery, which is light and thin, is excellent in moistureproof property and durability, further has good insulation performance, and does not cause leakage of current, and a durable, high-performance solar battery using the aforementioned backside covering member as the back side protective member.
A backside covering member for solar battery of the present invention is used as a protective member for protecting back sides of solar cells of a solar battery, and is made by integrally laminating an outer film and a moistureproof film with ethylene-vinyl acetate copolymer (EVA) adhesives, wherein the moistureproof film is constituted of a base film and a coating layer of an inorganic oxide deposited on a surface of the base film.
The backside covering member for solar battery of the present invention is light and thin because it dose not employ any glass plate.
The moistureproof film has a coating layer of an inorganic oxide deposited on a surface of the base film, thereby obtaining high moistureproof property. In addition, since the moistureproof film is insulative, there is no possibility of current leakage. EVA adhesives having excellent adhesive property is used for integrally laminating the moistureproof film to the outer film, thereby improving the durability.
A backside covering and sealing member for solar battery of the present invention functions as a back side protective member of the solar battery and is made by integrally laminating the backside covering member for solar battery of the present invention and an ethylene-vinyl acetate copolymer film together, wherein the ethylene-vinyl acetate copolymer film is laminated to a surface of the backside covering member opposite to the outer film.
A solar battery of the present invention comprises solar cells which are sealed between a front side protective member and a back side protective member. The back side protective member is the backside covering member of the present invention.